jdk8-mips64-public/hotspot: src/share/vm/memory/sharedHeap.hpp@8b10f48633dc (annotated)

src/share/vm/memory/sharedHeap.hpp@8b10f48633dc (annotated)

src/share/vm/memory/sharedHeap.hpp

Mon, 20 Sep 2010 14:38:38 -0700

author: jmasa
date: Mon, 20 Sep 2010 14:38:38 -0700
changeset 2188: 8b10f48633dc
parent 1907: c18cbe5936b8
child 2314: f95d63e2154a
permissions: -rw-r--r--

6984287: Regularize how GC parallel workers are specified.
Summary: Associate number of GC workers with the workgang as opposed to the task.
Reviewed-by: johnc, ysr

 /*
  * Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 // A "SharedHeap" is an implementation of a java heap for HotSpot.  This
 // is an abstract class: there may be many different kinds of heaps.  This
 // class defines the functions that a heap must implement, and contains
 // infrastructure common to all heaps.
 class PermGen;
 class Generation;
 class BarrierSet;
 class GenRemSet;
 class Space;
 class SpaceClosure;
 class OopClosure;
 class OopsInGenClosure;
 class ObjectClosure;
 class SubTasksDone;
 class WorkGang;
 class FlexibleWorkGang;
 class CollectorPolicy;
 class KlassHandle;
 class SharedHeap : public CollectedHeap {
   friend class VMStructs;
   friend class VM_GC_Operation;
   friend class VM_CGC_Operation;
 private:
   // For claiming strong_roots tasks.
   SubTasksDone* _process_strong_tasks;
 protected:
   // There should be only a single instance of "SharedHeap" in a program.
   // This is enforced with the protected constructor below, which will also
   // set the static pointer "_sh" to that instance.
   static SharedHeap* _sh;
   // All heaps contain a "permanent generation."  This is some ways
   // similar to a generation in a generational system, in other ways not.
   // See the "PermGen" class.
   PermGen* _perm_gen;
   // and the Gen Remembered Set, at least one good enough to scan the perm
   // gen.
   GenRemSet* _rem_set;
   // A gc policy, controls global gc resource issues
   CollectorPolicy *_collector_policy;
   // See the discussion below, in the specification of the reader function
   // for this variable.
   int _strong_roots_parity;
   // If we're doing parallel GC, use this gang of threads.
   FlexibleWorkGang* _workers;
   // Number of parallel threads currently working on GC tasks.
   // O indicates use sequential code; 1 means use parallel code even with
   // only one thread, for performance testing purposes.
   int _n_par_threads;
   // Full initialization is done in a concrete subtype's "initialize"
   // function.
   SharedHeap(CollectorPolicy* policy_);
   // Returns true if the calling thread holds the heap lock,
   // or the calling thread is a par gc thread and the heap_lock is held
   // by the vm thread doing a gc operation.
   bool heap_lock_held_for_gc();
   // True if the heap_lock is held by the a non-gc thread invoking a gc
   // operation.
   bool _thread_holds_heap_lock_for_gc;
 public:
   static SharedHeap* heap() { return _sh; }
   CollectorPolicy *collector_policy() const { return _collector_policy; }
   void set_barrier_set(BarrierSet* bs);
   // Does operations required after initialization has been done.
   virtual void post_initialize();
   // Initialization of ("weak") reference processing support
   virtual void ref_processing_init();
   void set_perm(PermGen* perm_gen) { _perm_gen = perm_gen; }
   // This function returns the "GenRemSet" object that allows us to scan
   // generations; at least the perm gen, possibly more in a fully
   // generational heap.
   GenRemSet* rem_set() { return _rem_set; }
   // These function return the "permanent" generation, in which
   // reflective objects are allocated and stored.  Two versions, the second
   // of which returns the view of the perm gen as a generation.
   PermGen* perm() const { return _perm_gen; }
   Generation* perm_gen() const { return _perm_gen->as_gen(); }
   // Iteration functions.
   void oop_iterate(OopClosure* cl) = 0;
   // Same as above, restricted to a memory region.
   virtual void oop_iterate(MemRegion mr, OopClosure* cl) = 0;
   // Iterate over all objects allocated since the last collection, calling
   // "cl->do_object" on each.  The heap must have been initialized properly
   // to support this function, or else this call will fail.
   virtual void object_iterate_since_last_GC(ObjectClosure* cl) = 0;
   // Iterate over all spaces in use in the heap, in an undefined order.
   virtual void space_iterate(SpaceClosure* cl) = 0;
   // A SharedHeap will contain some number of spaces.  This finds the
   // space whose reserved area contains the given address, or else returns
   // NULL.
   virtual Space* space_containing(const void* addr) const = 0;
   bool no_gc_in_progress() { return !is_gc_active(); }
   // Some collectors will perform "process_strong_roots" in parallel.
   // Such a call will involve claiming some fine-grained tasks, such as
   // scanning of threads.  To make this process simpler, we provide the
   // "strong_roots_parity()" method.  Collectors that start parallel tasks
   // whose threads invoke "process_strong_roots" must
   // call "change_strong_roots_parity" in sequential code starting such a
   // task.  (This also means that a parallel thread may only call
   // process_strong_roots once.)
   //
   // For calls to process_strong_roots by sequential code, the parity is
   // updated automatically.
   //
   // The idea is that objects representing fine-grained tasks, such as
   // threads, will contain a "parity" field.  A task will is claimed in the
   // current "process_strong_roots" call only if its parity field is the
   // same as the "strong_roots_parity"; task claiming is accomplished by
   // updating the parity field to the strong_roots_parity with a CAS.
   //
   // If the client meats this spec, then strong_roots_parity() will have
   // the following properties:
   //   a) to return a different value than was returned before the last
   //      call to change_strong_roots_parity, and
   //   c) to never return a distinguished value (zero) with which such
   //      task-claiming variables may be initialized, to indicate "never
   //      claimed".
  private:
   void change_strong_roots_parity();
  public:
   int strong_roots_parity() { return _strong_roots_parity; }
   // Call these in sequential code around process_strong_roots.
   // strong_roots_prologue calls change_strong_roots_parity, if
   // parallel tasks are enabled.
   class StrongRootsScope : public MarkingCodeBlobClosure::MarkScope {
   public:
     StrongRootsScope(SharedHeap* outer, bool activate = true);
     ~StrongRootsScope();
   };
   friend class StrongRootsScope;
   enum ScanningOption {
     SO_None                = 0x0,
     SO_AllClasses          = 0x1,
     SO_SystemClasses       = 0x2,
     SO_Symbols             = 0x4,
     SO_Strings             = 0x8,
     SO_CodeCache           = 0x10
   };
   FlexibleWorkGang* workers() const { return _workers; }
   // Sets the number of parallel threads that will be doing tasks
   // (such as process strong roots) subsequently.
   virtual void set_par_threads(int t);
   // Number of threads currently working on GC tasks.
   int n_par_threads() { return _n_par_threads; }
   // Invoke the "do_oop" method the closure "roots" on all root locations.
   // If "collecting_perm_gen" is false, then roots that may only contain
   // references to permGen objects are not scanned.  If true, the
   // "perm_gen" closure is applied to all older-to-younger refs in the
   // permanent generation.  The "so" argument determines which of roots
   // the closure is applied to:
   // "SO_None" does none;
   // "SO_AllClasses" applies the closure to all entries in the SystemDictionary;
   // "SO_SystemClasses" to all the "system" classes and loaders;
   // "SO_Symbols" applies the closure to all entries in SymbolsTable;
   // "SO_Strings" applies the closure to all entries in StringTable;
   // "SO_CodeCache" applies the closure to all elements of the CodeCache.
   void process_strong_roots(bool activate_scope,
                             bool collecting_perm_gen,
                             ScanningOption so,
                             OopClosure* roots,
                             CodeBlobClosure* code_roots,
                             OopsInGenClosure* perm_blk);
   // Apply "blk" to all the weak roots of the system.  These include
   // JNI weak roots, the code cache, system dictionary, symbol table,
   // string table.
   void process_weak_roots(OopClosure* root_closure,
                           CodeBlobClosure* code_roots,
                           OopClosure* non_root_closure);
   // The functions below are helper functions that a subclass of
   // "SharedHeap" can use in the implementation of its virtual
   // functions.
 public:
   // Do anything common to GC's.
   virtual void gc_prologue(bool full) = 0;
   virtual void gc_epilogue(bool full) = 0;
   //
   // New methods from CollectedHeap
   //
   size_t permanent_capacity() const {
     assert(perm_gen(), "NULL perm gen");
     return perm_gen()->capacity();
   }
   size_t permanent_used() const {
     assert(perm_gen(), "NULL perm gen");
     return perm_gen()->used();
   }
   bool is_in_permanent(const void *p) const {
     assert(perm_gen(), "NULL perm gen");
     return perm_gen()->is_in_reserved(p);
   }
   // Different from is_in_permanent in that is_in_permanent
   // only checks if p is in the reserved area of the heap
   // and this checks to see if it in the commited area.
   // This is typically used by things like the forte stackwalker
   // during verification of suspicious frame values.
   bool is_permanent(const void *p) const {
     assert(perm_gen(), "NULL perm gen");
     return perm_gen()->is_in(p);
   }
   HeapWord* permanent_mem_allocate(size_t size) {
     assert(perm_gen(), "NULL perm gen");
     return _perm_gen->mem_allocate(size);
   }
   void permanent_oop_iterate(OopClosure* cl) {
     assert(perm_gen(), "NULL perm gen");
     _perm_gen->oop_iterate(cl);
   }
   void permanent_object_iterate(ObjectClosure* cl) {
     assert(perm_gen(), "NULL perm gen");
     _perm_gen->object_iterate(cl);
   }
   // Some utilities.
   void print_size_transition(outputStream* out,
                              size_t bytes_before,
                              size_t bytes_after,
                              size_t capacity);
 };

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/memory/sharedHeap.hpp@8b10f48633dc (annotated)

src/share/vm/memory/sharedHeap.hpp